1. Field of the Invention
The present invention relates to a shift device for switching a dog clutch mechanism in a transmission.
2. Description of the Prior Art
FIG. 11 shows a shift device of a gear transmission described in JP Laid-open Publication No. 2006-082737. The shift device includes: a shift shaft 302, a shift fork 303 fixed to the shift shaft 302 and a shift sleeve 304 engaging with the shift fork 303. The shift shaft 302 is supported by a transmission case 301 so as to be movable in an axial directional of the shift shaft 302. A drive pin 308 of the shift fork 303 engages with an inner lever 307 fixed to the lower end portion of a lever shaft 306. The lever shaft 306 is free-rotatably supported by the transmission case 302. The lever shaft 306 is connected to a shift lever device through an outer lever 310 and a shift operation force transmission mechanism (not shown).
A waiting mechanism includes a coil spring 320 fit onto an outer peripheral surface of the lever shaft 306. One end part of the coil spring 320 engages with the drive pin 308 and the other end part engages with the lever shaft 306 or the inner lever 307. Further, a ball type detent mechanism 321 is provided in the shift shaft 302.
According to the configuration of FIG. 11, it is required to fit the coil spring 320 onto the outer peripheral surface of the lever shaft 306 before the lever shaft 306 is attached in an inside of the transmission case 301. Namely, the lever shaft 306 onto which the coil spring 320 has been fit need be attached in the inside of the transmission case 301, therefore an attachment work takes time and effort. Further, the work of removing the coil spring 320 also takes time and effort.
The coil spring 320 is arranged in an upstream of an operation force transmission path relative to the detent mechanism 321. Thus, a spring load of the coil spring 320 should be set greater than a load with which the detent mechanism 321 holds the shift shaft 302. Otherwise, the coil spring 320 would be twisted always during a shift operation so that a transmission of the shift operation force would become slow. Further, a configuration that the load is generated by the twist operation of the coil spring 320 causes a size increase in the coil spring 320.
FIG. 12 shows a shift device of a gear transmission described in U.S. Pat. No. 8,276,473. Two shift shafts 402 and 403 are fixed to a transmission case 401 so as not to be able in an axis-directional. Then, shift forks 404, 405, and 406 are fit onto the shift shafts 402 and 403o as to be movable in the axial direction. Coil springs 411 and 412 for waiting mechanism are fit onto outer peripheral surfaces of the shift shafts 402 and 403 so as to bias the shift forks 404, 405, and 406 in the axial direction. Further, a shift drum 415 is arranged for driving the shift forks 404, 405, and 406 in the axial direction. Then, a waiting mechanism 416 is arranged in the shift drum 415.
According to the configuration of FIG. 12, similarly to the case of FIG. 11, it is required to fit the coil springs 411 and 412 onto the outer peripheral surface of the shift shafts 402 and 403 before the shift shafts 402 and 403 are attached in an inside of the transmission case 401. Namely, the shift shafts 402 and 403 onto which the coil springs 411 and 412 have been fit need be attached in the inside of the transmission case 401, therefore an attachment work takes time and effort. Further, the work of removing the coil springs 411 and 412 also take time and effort.